Control circuits can use pulse width modulated (PWM) signals to control other electronic circuits. Feedback systems can include such control circuits to adjust various characteristics of a PWM signal, for example, to adjust the duty cycle of the PWM signal. Such control circuits are useful, for example, in power converter circuits such as DC-DC boost converters that use rapid switching of a transistor controlled by a PWM signal.
Some conventional control circuits compare a saw tooth signal to an output signal and adjust the duty cycle of a PWM control signal based on the comparison. Some conventional systems vary the duty cycle of a PWM control signal varying the “on” time or the “off” time of the control signal. Some conventional systems use a microcontroller executing software as a control circuit; these systems can require an analog to digital converter (ADC).